Component feeding is a well-known process in Surface Mounting Technology (SMT). In general, a feeder is used to sequentially supply surface mountable electrical components to a pick up location for subsequent placing, by a pick-and-place machine, onto a Printed Circuit Board (PCB) which is pre-printed with solder paste.
One form of feeder is a tape and reel feeder in which the electrical components are packaged on a tape that is wound onto a reel. The tape comprises individual pockets each containing one of the electrical components that are individually sealed in the pockets by a covering of thin film. In use, the film is removed when the tape enters the pick up location therefore leaving a pocket containing one of the electrical components in a position accessible by the pick-and-place machine. Unfortunately, the tape is substantially wider than the components located in the pockets which therefore increases the width of the feeder. Further, the reel and apparatus for removing the film also adds to the width and overall size of the feeder.
Hopper feeders also known as bulk or tube feeders are an alternative to tape and reel feeders. Hopper feeders comprise a hopper in communication, along a downwardly sloping passage, with the pick up location. The downwardly sloping passage makes use of gravity for supplying the components to the pick up location. To further assist the supplying of the components to the pick up location a combination of gravity and air blasting has also been used.
The pick up location of such hopper feeders has an abutment wall and an aperture. The abutment wall abuts the components supplied from the hopper before they are removed, through the aperture, by the pick-and-place machine. The supply of components to the pick up location must be controlled, otherwise undesirable amounts of friction between the abutment wall and an abutting component can result. This friction is due to a mass of stacked components in the downwardly sloping passage pushing the abutting components into the abutment wall. Accordingly, this friction may cause problems when the pick-and-place machine attempts to remove the abutting component. Further, unnecessary friction between the abutting component and an adjacent component can further hinder the removal of the abutting component.
In order to reduce the friction described above, the supply of components to the pick up location is mechanically controlled to separate components in the downwardly sloping passage from a component in the pick up location. For example, one conventional approach is to use a pneumatically controlled slotted disk located horizontally in series between the pick up location and sloping passage. The slotted disk has two diametrically opposite slots for sequentially engaging a component. The disk rotates through 180 degrees in a timed sequence to thereby transport an individual component, engaged in one of the slots, from the passage to the pick up location.
In use, both conventional hopper feeders or tape and reel feeders are positioned on either sides of a conveyor track extending along a length of a pick-and-place machine. The conveyor track transports printed circuit boards into an area of the pick-and-place machine to allow components, fed from the hopper feeders or tape and reel feeders, to be mounted to the circuit boards. Such pick-and-place machines are expensive and their high speed moving parts are subject to wear and high maintenance costs. Further, each component is sequentially mounted to the printed circuit board which is time consuming and therefore can result in increased manufacturing overheads.
In U.S. Pat. No. 4,451,324 there is disclosed an apparatus for placing electronic components on a circuit board. This apparatus has a template which is supplied with components from hoppers. The template is then moved to a position in alignment with and adjacent to the circuit board to allow connector pads of the components on the template to be aligned with corresponding pads located on an underside of the circuit board. The combination of the template and board are then rotated 180 degrees so that the components are located on top of the circuit board. The template is then removed and the components connector pads can then be soldered to the corresponding pads on the board. Although this apparatus concurrently places electronic components on a circuit board, it is unnecessarily slow due to the required movement of the template to the position in alignment with and adjacent to the circuit board. Delays are also caused by the rotation of the template and board which may also cause component misalignment.